The field of this invention is the apparatus for hoisting and positioning prefabricated tilt-up concrete slabs. More specifically, the invention relates to improvements in clutch assemblies of such apparatus.
Prefabricated concrete walls or panels are common components of building constructions. Such panels are generally cast in a horizontal position where they are allowed to set. The hoisting and positioning of the finished panel presents problems in that the panels are very heavy and difficult to handle without cracking or breaking. Preliminary attempts to solve this problem can be found in U.S. Pat. No. 3,883,170, to Fricker et al., disclosing the use of an anchor imbedded in a concrete slab as a point of attachment and lifting in combination with a hoisting shackle, and in U.S. Pat. Nos. 4,367,892 and 4,437,642, to Holt, disclosing the use of a t-shaped anchor also for use with a hoisting shackle.